M&S says

For schoolwear that keeps up with them, these belted skinny leg trousers for children tick all the right boxes. A clever Weather Repellent finish protects them from unexpected showers and splashes while out on the playground, while the Crease Resistant fabric keeps them looking neat and tidy even after a big day at school. The regular fit and adjustable waist help create the perfect fit for them, keeping them comfortable and ready to learn in these school trousers.

35 days to return
You may return unused products within 35 days of purchase with a valid parcel summary document. Your items don't need to be in the original box or bag as long as they're securely packaged.

How to return
It’s easy to return items to M&S. Simply print the returns label, attach it to the top of your parcel and insert the returns note in the parcel. Drop your parcel at a local post office. We will automatically deduct the cost of return from your refund.